The present invention relates to a method of coating cutting tool inserts with a layer of an iron group metal. Inserts with a coating applied according to the invention are particularly suitable for brazing.
Cemented carbide inserts are generally attached to tool-holders by mechanical means if possible. In case of saw-blades, drills and circular cutters, the design does not permit mechanical clamps and/or similar mechanical attachments. In these cases the inserts have to be brazed to the toolholder.
When brazing cemented carbide with a low binder content there are problems with the wetting of the braze and therefore the inserts have to be coated with cobalt prior to the brazing procedure. For coating on industrial scale, this cobalt coating is generally made electrolytically. However, such coating generally has poor adherence. In order to improve the adhesion, the inserts are heat treated in a subsequent production step. This coating method is rather complex and expensive and the resultant coating adhesion is still not always satisfactory.